Water conservation is increasingly important. Water supplies are essentially constant and more people are using the same water every year. In the United States, a substantial portion of the water supply is used to maintain landscape (trees, grass, etc.). Irrigation studies show that much of the water applied to the landscape by prevalent irrigation methods is wasted. Excess water ends tip as surface run-off or seepage into the ground.
Water lost as such is rarely captured and reused. Instead, surface run-off typically requires erosion control measures and often impacts mosquito abatement efforts. Seepage into the ground may pollute ground water with fertilizer and pesticides
Reducing water loss for a landscape is a complex process. Soil types hold varying amounts of water and not all of the water held by the soil is available to the landscape. Landscape has varying water needs depending on whether the landscape is full sun, partial sun, or shady locations. Air temperature and humidity also play roles in determining how much water the landscape needs. The ground slope may affect the amount of water to apply to the landscape.
Soil moisture sensors have been used in the past. However, these sensors have been too expensive and/or inaccurate due to the variations in soil properties (e.g., composition, chemistry, compaction and temperature).
Although a Soil Moisture Neutron Probe (SMNP) has been shown to be fairly accurate, the public typically will not accept the use of neutron sources in their yards. Documentation and disposal issues are also a concern. Relative permittivity measurements using either a TDR method or a capacitive method have also been shown to be an effective indicator of volumetric water content. However, both methods have drawbacks.